Atomic layer deposition apparatus using neutral beam and method of depositing atomic layer using the same

ABSTRACT

Disclosed are an atomic layer deposition apparatus using a neutral beam and a method of depositing an atomic layer using the apparatus, capable of converting an ion beam into a neutral beam and radiating it onto a substrate to be treated. The method uses an apparatus for supplying a first reaction gas containing a material that cannot be chemisorbed onto a substrate to be treated into a reaction chamber in which the substrate is loaded, and forming a first reactant adsorption layer containing a material that cannot be chemisorbed onto the substrate; and radiating a neutral beam generated by the second reaction gas onto the substrate on which the first reactant adsorption layer is formed, and removing a material not chemisorbed onto the substrate from the first reactant adsorption layer to form a second reactant adsorption layer. It is possible to perform a process without damage due to charging with the apparatus for depositing an atomic layer using a neutral beam and the method of depositing an atomic layer using the apparatus.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

South Korea Priority Application 10-2005-0023782, filed Mar. 22, 2005including the specification, drawings, claims and abstract, isincorporated herein by reference in its entirety. This application is aContinuation of U.S. application Ser. No. 11/348,471, filed Feb. 7,2006, incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an atomic layer deposition apparatususing a neutral beam and a method of depositing an atomic layer usingthe apparatus, and more particularly, to an atomic layer depositionapparatus using a neutral beam and a method of depositing an atomiclayer using the apparatus in which a second reaction gas is ionized toform plasma, and a resulting flux of radicals, i.e. an ion beam, isneutralized and radiated onto a substrate to be treated.

2. Description of the Prior Art

Due to increasing demand for highly integrated semiconductor devices,recent years have seen continuous reduction of a semiconductorintegrated circuit design rule to the point of a critical dimension notmore than 90 nm. Nowadays, in order to implement such nanometer-scalesemiconductor devices, ion enhancement equipment such as a high densityplasma apparatus, a reactive ion etcher, and so on are being widelyused. However, such equipment may cause physical and electrical damageto a semiconductor substrate or a specific material layer on thesemiconductor substrate, since it involves vast quantities of ions forperforming an etching (or deposition) process colliding with thesemiconductor substrate or specific material layer with hundreds eV ofenergy.

For example, the surface layer of a crystalline substrate or a specificmaterial layer bombarded with ions may be converted into an amorphouslayer, some incident ions are adsorbed or some components of thebombarded material layer are selectively decomposed, so that thechemical composition of an etched (or deposited) surface layer ischanged. In addition, atomic bonds of the surface layer are damaged bythe bombardment, thereby becoming dangling bonds. Such dangling bondsmay cause physical or electrical damage to the material, or give rise tocharge-up damage of a gate insulating layer or electrical damage bynotching of polysilicon due to charging of photoresist. In addition tosuch physical and electrical damage, there occurs either surfacecontamination caused by a chamber material, or surface contaminationcaused by reaction gases such as C—F polymers generated when using aCF-based reaction gas.

Therefore, since the physical/electrical damage caused by such ions inthe nanometer-scale semiconductor devices decreases reliability andproductivity of the semiconductor devices, it is required to develop aninnovative semiconductor etching (or depositing) apparatus and methodthat may be applied in the future according to the trend of the highintegration of the semiconductor devices and resulting reduction of thedesign rule.

As an example of such requirement, D. B. Oakes et al. propose adamage-free etching technology using a hyperthermal atomic beam in thepaper titled “Selective, Anisotropic and Damage-Free SiO₂ Etching with aHyperthermal Atomic Beam.” As another example, Takashi Yunogami et al.propose a silicon oxide etching technology with little damage using aneutral beam and a neutral radical in the paper titled “Development ofNeutral-Beam-Assisted Etcher” (J. Vac. Sci. Technol. A 13(3), May/June,1995). For still another example, M. J. Goeckner et al. propose anetching technology using an overheated, charge-free neutral beam insteadof plasma in the paper titled “Reduction of Residual Charge inSurface-Neutralization-Based Beams” (2^(nd) International Symposium onPlasma Process-Induced Damage, May 13-14, 1997, Monterey, Calif.).

In the process of fabricating the semiconductor devices, a sputteringmethod, a chemical vapor deposition (CVD) method, and an atomic layerdeposition (ALD) method are generally employed in order to uniformlydeposit a thin layer. In the sputtering method, an inert gas such asargon is converted into plasma to sputter a target surface, therebyforming a highly pure, thin layer having excellent adhesion. However,the sputtering method makes it very difficult to obtain uniformityacross the entire thin layer.

In the CVD method, most widely used nowadays, various gases are suppliedand induced by high energy in the form of intense heat, light, or plasmato chemically react to form a thin layer of desired thickness. While CVDhas the advantages of excellent step coverage and high yield, atemperature of the thin layer during its formation is very high, and thethickness of the thin layer cannot be controlled to a precision ofseveral A. In addition, since at least two kinds of reaction gas aresimultaneously supplied into a reactor, particles may be generated,which may be a source of contamination.

Meanwhile, in the ALD method, a reaction gas and a purge gas arealternately supplied to deposit a thin layer one atomic layer unit at atime. The precise thickness control afforded by the atomic layer unitsis suggested to overcome the limitations of CVD in scaled-downsemiconductor processes requiring ever thinner layers. Using ALD, it ispossible to obtain a thin layer having a uniform thickness that can befinely adjusted to a precision of an atomic layer unit, and suppressgeneration of particles, a source of contamination.

However, the ALD process makes also use of a second reaction gas that isinjected to induce reaction at high temperature, or that is ionized toconvert a flux of plasma. At this time, charging due to ions orelectrons may occur as a result of using the plasma. In addition, whenthe second reaction gas is injected as is, a second reaction gas processperformed at high temperature is added to the ALD process.

Further, while a method of using remote plasma has been developed tosolve the problem of charging, in such a method, flux and energy may bereduced.

SUMMARY

The present invention provides an atomic layer deposition (ALD)apparatus using a low-temperature neutral beam formed with energeticradicals (overheated). The beam may be generated by reflecting energeticions at a reflective body, re-bonding, or charge exchange, and can beadapted to an ALD process, especially a second reaction gas process.

The present invention also provides a method of depositing an atomiclayer without charging a second reaction gas by plasma ions, i.e.,without electrical damage, by ionizing and neutralizing the secondreaction gas before radiating it onto a substrate to be treated.

The present invention further provides a method of depositing an atomiclayer using a neutral beam without charging a second reaction gas, byusing an electrically neutral flux of radicals which have higher energythan conventional remote plasma.

According to an aspect of the present invention, there is provided anapparatus for depositing an atomic layer using a neutral beam including:an ion source extracting an ion beam having a polarity from a gasinjected through an inlet; a reaction chamber into which a gas can beinjected through the inlet, and that can locate a substrate to betreated on a path of the neutral beam; a grid assembly located at oneend of the ion source and having a plurality of grid holes acceleratinga specific polarity of ion beam; and a reflective body having aplurality of reflective body holes or slits corresponding to the gridholes of the grid assembly, and reflecting the ion beam passing throughthe grid holes inside the reflective body holes or the slits to convertthe ion beam into a neutral beam, wherein a first reaction gas isinjected into the reaction chamber to react with the substrate, and thena second reaction gas is injected through the inlet of the ion source tobe converted into a neutral beam and radiated onto the substrate.

According to another aspect of the present invention, there is provideda method of depositing an atomic layer using a neutral beam including:supplying a first reaction gas containing a material that cannot bechemisorbed onto a substrate to be treated into a reaction chamber inwhich the substrate is loaded, and forming a first reactant adsorptionlayer containing a material that cannot be chemisorbed onto thesubstrate; and radiating a neutral beam generated from the secondreaction gas onto the substrate on which the first reactant adsorptionlayer is formed, and removing a material not chemisorbed onto thesubstrate from the first reactant adsorption layer to form a secondreactant adsorption layer.

According to still another aspect of the present invention, there isprovided a method of depositing an atomic layer using a neutral beamthat enables deposition of a single atomic layer containing Si, nitride,metal oxide, or a metal layer, the method comprising: supplying a firstreaction gas containing a material that cannot be chemisorbed onto asubstrate to be treated into a reaction chamber in which the substrateis loaded, and forming a first reactant adsorption layer containing amaterial that cannot be chemisorbed onto the substrate; and radiating aneutral beam generated by the second reaction gas onto the substrate onwhich the first reactant adsorption layer is formed, and removing amaterial not chemisorbed onto the substrate from the first reactantadsorption layer to form a second reactant adsorption layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic diagram illustrating an apparatus for depositingan atomic layer using a neutral beam in accordance with an exemplaryembodiment of the present invention;

FIG. 2 is a schematic perspective view illustrating an ion source of thedeposition apparatus shown in FIG. 1;

FIG. 3 is a schematic perspective view illustrating a neutral beamgenerating part (a reflective body) of the deposition apparatus shown inFIG. 1; and

FIG. 4 is a flowchart showing a process of depositing an atomic layerusing the atomic layer deposition apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the accompanying drawings. In the followingdescription and the drawings, the same reference numerals are used todesignate the same or similar components, and such components will bedescribed only once.

FIG. 1 is a schematic diagram illustrating an apparatus for depositingan atomic layer using a neutral beam in accordance with an exemplaryembodiment of the present invention, FIG. 2 is a perspective viewillustrating an ion source and a grid shown in FIG. 1, and FIG. 3 is aperspective view illustrating a reflective body shown in FIG. 1.

One aspect of the present invention provides more preferable conditionsthan the ALD process of a nanometer-scale semiconductor device on thetheoretical basis of a neutral beam, which will be described withreference to FIGS. 1 to 3.

In FIG. 1, an ion beam generated from an ion source 10 passes through aplurality of grid holes 14 a. Then, the ion beam is reflected on aninner surface of each reflective body hole 42, converted into a neutralbeam, and finally radiates a specific material layer on a substrate 20to be treated.

The ion source 10 functions to generate the ion beam from variousreaction gases injected through a gas inlet 11. In the present exemplaryembodiment, the ion source 10 employs an inductively coupled plasma(ICP) generator, a capacitively coupled RF ion source, a helical wavebond ion source, a negative ion source, or an electron-cyclotron reactor(ECR), for generating plasma by applying inductive current to aninduction coil 12, which may use variously deformed ion sources.

Installed at a rear end of the ion source 10 is a grid assembly 14having the plurality of grid holes 14 a through which the ion beampasses and is accelerated by an applied voltage.

A reflective body 40 for reflecting the incident ion beam to convert itinto a neutral beam is securely attached to a rear end of the gridassembly 14. The reflective body 40 may be formed of a conductivematerial such as semiconductor, metal, and so on. Only a surface of thereflective body holes 42 in the reflective body 40 may be formed of theconductive material. In addition, the reflective body 40 may be formedof a mirror surface of a conductive material such as diamond like carbon(DLC), glassy carbon, and so on, or a metal substrate.

Meanwhile, the reflective body holes 42 are tilted to a certain anglewith respect to the ion beam such that the ion beam passing straightthrough the grid holes is reflected inside the reflective body holes 42.

The reflective body 40 is preferably ground in order to dischargecharges generated by the incident ion beam. In addition, while thereflective body 40 is shown in FIG. 3 to have a cylindrical shape, itsshape is not limited and may be rectangular or polygonal.

Further, while the reflective body holes 42 are also shown in FIG. 3 tohave a cylindrical shape, their shape too is not limited and may berectangular or polygonal.

In particular, when an etching apparatus is manufactured, as disclosedin Korean Patent Application No. 2003-42116, filed on Jun. 26, 2003 bythe present applicant, slits are formed in the reflective body, insteadof the reflective body holes. Using the slits, it is possible toovercome problems due to a narrow space of the reflective body. Herein,“reflection boy holes” includes various shapes of reflective body holesand slits.

Meanwhile, the reflective body holes are tilted such that the ion beampassing straight through the grid holes is reflected inside thereflective body holes 42 only once. In the exemplary embodiment, thereflective body holes are tilted such that the ion beam is incident onthe inner surface of the reflective body holes at an incident angle ofno more than 15°, and preferably 3°-15°. The incident angle of the ionbeam having a range of 3°-15° means that the ion beam is incident at anangle of 75°-87° with respect to the inner surface of the reflectivebody holes.

In addition, the neutral beam reflected by the surface of the reflectivebody 40 inside the reflective body holes 42 has a reflection angle of nomore than 40°, and preferably 5-40°.

According to the above-referenced prior application of the presentapplicant, it will be appreciated that an optimal amount of neutral beamflux can be obtained by adjusting the incident angle and reflectionangle.

Meanwhile, a substrate 20 to be treated is disposed on a propagationpath of the neutral beam reflected and converted by the reflective body40. The substrate 20 is mounted on a stage 60 in a reaction chamber 50maintained in a constant vacuum state by a vacuum device (not shown).The stage 60 may be disposed in a direction perpendicular to the neutralbeam and capable of tilting to control the angle of the substrate 20according to the kind of deposition process. In addition, a gas inlet 51is formed in the reaction chamber 50 to inject various gases, and aheater 61 is installed at the stage 60 to heat the substrate 20.

An ALD process performed in an atomic layer deposition apparatus using aneutral beam in accordance with an exemplary embodiment of the presentinvention will now be described.

In the present exemplary embodiment, a halogenic element that is notchemisorbed onto the substrate 20 is selected. Therefore, a gascontaining the halogenic element is selected as a first reaction gas, agas that can react with the halogenic element to remove it from thesubstrate is selected as a second reaction gas, and a purge gas forpurging the reaction chamber 50 of the halogenic element and otherbyproducts is selected as an inert gas that does not react with amaterial deposited on the substrate 20. The above gases may vary indifferent embodiments of the invention.

Hereinafter, method of depositing a thin layer using an ALD process inaccordance with an exemplary embodiment of the present invention will bedescribed with reference to FIGS. 4A to 4D, which are cross-sectionalviews showing steps of treating a substrate 20 according to the method.

First, referring to FIG. 4A, a first reaction gas 21 required to form athin layer for manufacturing a semiconductor device is supplied onto thesubstrate 20 to form a first reactant adsorption layer 22. The firstreaction gas 21 is a precursor generally containing a halogenic elementsuch as Cl. As a result, the first reactant adsorption layer 22containing a halogenic element chemisorbed onto the substrate 20 isformed (a first reaction gas process).

The first reaction gas process will be described below in detail.

After loading the treated substrate 20 onto the stage 60 including theheater 61 in the reaction chamber 50, the heater 61 is operated tomaintain the reaction chamber 50 or the substrate 20 at a temperature ofno more than 450° and a chamber pressure of no more than 1 ton. In thisstate, a first reaction gas 21 required to form a silicon layer, e.g.,SiCl₄, is supplied into the reaction chamber 50 through the inlet 51 for60 seconds. As a result, a first reactant adsorption layer 22 havingSi—Cl bonds in which a silicon atom is chemisorbed is formed on thesubstrate 20.

Meanwhile, according to the kind of thin layer to be formed on thesubstrate 20, the first reaction gas may be a metal-halogenic elementsuch as SiCl4, TiCl₄, SiH₂Cl₂, Si₂Cl₆, TaCl₃, AlCl₃, Al(CH₃)₂Cl, ZrCl₄,HfCl₄ and so on.

For example, when a silicon nitride layer or a silicon oxide layer is tobe formed on the substrate 20, a silicon source gas such as SiCl₄,SiH₂Cl₂ or Si₂Cl₆ may be supplied as the first reaction gas 21. When aTa₂O₅ layer is to be formed on the substrate 20, TaCl₃ may be suppliedas the first reaction gas 22. In addition, when an Al₂O₃ layer is to beformed on the substrate 20, AlCl₃ may be supplied as the first reactiongas 21.

Meanwhile, using the first reaction gas, a single atomic layer such asSi, a nitride layer such as TiN, SiN, ZrN, TaN, GaN, WN, WBN, Ya₃N₅,WSiN, TiSiN, TaSiN, AISiN, AITiN, and so on, a metal layer such as Al,Cu, Mo, Ir, W, Ag, Ta, Pt, Ir, and a metal oxide layer such as Ta₂O₅,Ta₂O₃, TiO₂, ZrO₂, HfO₂, Ya₂O₃, La₂O₃, Nb₂O₅, CeO₂, SiO₂, Al₂O₃, RuO₂,IrO₂, SrTiO₃, PbTiO₃, SrRuO₃, CaRuO₃, (Ba,Sr)TiO₃, Pb(Zr,Ti)O₃,(Pb,La)(Zr,Ti)O₃, (Sr,oCa)RuO₃, (Ba,Sr)RuO₃, and so on, may be formed.

Next, referring to FIG. 4B, in order to remove byproducts remaining onthe substrate, to which the first reactant adsorption layer 22containing a halogenic element is chemisorbed, an inert gas 23 such asN₂, argon or helium is supplied through the inlet 51 to purge thereaction chamber 50 of byproducts (a purge process). In order to removethe byproducts, a pumping process may be used, instead of the purgeprocess.

More specifically, an N₂ gas 23 is supplied for 30 seconds into thereaction chamber 50 and onto the substrate 20 having the first reactantadsorption layer 22 containing the Si—Cl bonds to remove byproductsremaining on the substrate 20 and purge the reaction chamber 50. Thebyproducts are discharged through an outlet (not shown).

Next, referring to FIG. 4C, a second reaction gas 24 that reacts with Clthat is not chemisorbed, for example, hydrogen gas (24), is suppliedonto the substrate 20 having the first reactant adsorption layer 22 (asecond reaction gas process).

Here, according to the first reaction gas which is not chemisorbed ontothe substrate 20, gases such as oxygen, nitrogen, CH-based gases (forexample, ammonia) and so on, may be supplied as the second reaction gas,alternatively to hydrogen.

Specifically, hydrogen gas 24 is supplied to an ion source 10 through aninlet 11 of the ion source 10, ionized by means of an RF device 12,accelerated to a reflective body 40 thereunder, and reflected bysurfaces of the reflection holes 42 in the reflective body 40 togenerate a neutral beam. Here, the neutralization reaction may begenerated by re-bonding or charge exchange, or the like, as well as thereflective body.

Then, the neutral beam reacts with a halogenic element, i.e., Cl, bondedto the first reactant adsorption layer 22 to remove the halogenicelement from the first reactant adsorption layer 22 so that the secondreactant adsorption layer 25 from which the halogenic element is removedremains on the substrate 20.

Here, the neutral beam is supplied for 60 seconds onto the substrate 20on which the first reactant adsorption layer 22 is formed, and 40 Wattsof RF power is applied to the RF device 12. At this time, a Cl atom isbonded to a hydrogen atom to form HCl and be separated from the firstreactant adsorption layer 22, and the second reactant adsorption layer25 formed purely of silicon remains on the substrate 20.

Then, referring to FIG. 4D, byproducts remaining on the substrate 20, onwhich the second reactant adsorption layer 25 without the halogenicelement is deposited, are removed (a purge process). As described withreference to FIG. 4D, the byproducts are purged using an inert gas 26 orremoved using a pumping process.

Specifically, in order to remove byproducts (HCL) remaining on thesubstrate 20, into which the second reactant adsorption layer 25containing a halogenic element is chemisorbed, an inert gas 26 such asCl is supplied through the inlet 51 to purge the reaction chamber 50 ofthe byproducts. In order to remove the byproducts, a pumping process maybe used, instead of the purge process.

More specifically, N₂ gas is supplied for 30 seconds onto the substrate20, on which the second reactant adsorption layer 25 containing HCL isformed, to remove the byproducts remaining on the substrate 20 and purgethe chamber. The byproducts are discharged through an outlet (notshown).

Meanwhile, a cycle comprised of the processes described with referenceto FIGS. 4A to 4D is repeated several times until a thin layer ofdesired thickness is obtained.

Therefore, the second reactant adsorption layer 25, e.g., apredetermined thickness of silicon layer 25, is deposited on thesubstrate 20.

As can be seed from the foregoing, in the atomic layer depositionapparatus using a neutral beam and method of depositing an atomic layerusing the apparatus in accordance with the present invention, it ispossible to perform an ALD process without damage due to charging, atlow temperature, by neutralizing various reactive or non-reactiveenergetic ions using reflection, re-bonding, and charge exchange with amaterial, and adapting the ions to the ALD process. In this process,materials such as a basic single atomic layer containing Si, and so on,various nitrides, metal oxides, and metal layers may be effectivelydeposited to form a gate dielectric layer (an oxide layer), a gateelectrode, a capacitor electrode, a capacitor dielectric layer, adiffusion barrier layer, a metal interconnection, and so on, in themanufacture of semiconductor devices.

While this invention has been described in detail with reference toexemplary embodiments thereof, it will be apparent to those of ordinaryskill in the art that various changes in form and detail may be madewithout departing from the scope and spirit of the invention as setforth in the appended claims.

1. An apparatus for depositing an atomic layer using a neutral beamcomprising: an ion source extracting an ion beam having a polarity froma gas injected through an inlet; a reaction chamber into which the gascan be injected through the inlet, and that can locate a substrate to betreated on a path of the neutral beam; a grid assembly located at oneend of the ion source and having a plurality of grid holes acceleratinga specific polarity of ion beam; and a reflective body having aplurality of reflective body holes or slits corresponding to the gridholes of the grid assembly, and reflecting the ion beam passing throughthe grid holes inside the reflective body holes or slits to convert theion beam into a neutral beam, wherein a first reaction gas is injectedinto the reaction chamber to react with the substrate, and then a secondreaction gas is injected through the inlet of the ion source to beconverted into a neutral beam and radiated onto the substrate.
 2. Theapparatus for depositing an atomic layer using a neutral beam accordingto claim 1, wherein the neutral beam is generated through reflection ofan energetic ion beam by a reflective body, re-bonding, or chargeexchange.
 3. The apparatus for depositing an atomic layer using aneutral beam according to claim 1, wherein each grid hole has a diameterequal to or larger than that of each reflective body hole or slit. 4.The apparatus for depositing an atomic layer using a neutral beamaccording to claim 1, wherein the reflective body holes or slits aretilted to a certain angle with respect to the ion beam such that the ionbeam passing straight through the grid holes is reflected inside thereflective body holes or slits.
 5. The apparatus for depositing anatomic layer using a neutral beam according to claim 1, wherein the ionsource is one of a capacitively coupled RF ion source, a helical wavebond ion source, a negative ion source, an electron-cyclotron reactor(ECR), and an inductively coupled plasma source.
 6. The apparatus fordepositing an atomic layer using a neutral beam according to claim 1,wherein the ion beam is incident on the inner wall of the reflectivebody holes or slits at an angle of no more than 15°.
 7. The apparatusfor depositing an atomic layer using a neutral beam according to claim1, wherein the ion beam is incident on the inner wall of the reflectivebody holes or slits at an angle of no more than 40°.
 8. The apparatusfor depositing an atomic layer using a neutral beam according to claim1, wherein the reflective body is formed of a mirror surface of aconductive material or a metal substrate selected from a semiconductorsubstrate, diamond like carbon (DLC), and glassy carbon.
 9. Theapparatus for depositing an atomic layer using a neutral beam accordingto claim, wherein a first reaction gas containing a material that ischemisorbed onto the substrate and a material that is not chemisorbedonto the substrate, and an inert gas are injected into the reactionchamber.
 10. The apparatus for depositing an atomic layer using aneutral beam according to claim 9, wherein the gas injected into the ionsource is a second reaction gas for removing a material that is notchemisorbed onto the substrate.
 11. The apparatus for depositing anatomic layer using a neutral beam according to claim 10, wherein, afterthe second reaction gas injected into the ion source is ionized to forman ion beam, the ion beam is converted into a neutral beam by reflectionfrom the reflective body, re-bonding, or charge exchange, and then theneutral beam is radiated onto the substrate to remove a material that isnot chemisorbed onto the substrate.